hotmustang331 said:
Exatcly, the dyno is for comparing #s that we KNOW. Its consistent.
You mean the Dynojet, right?
MD dyno is the only way to tune and the ONLY dyno that will get REAL WORLD A/F #s and the such.
I've said that I think the MD is useful for, and IMHO only for, tuning becuase of its ability to load the drivetrain, allowing a wide range of throttle inputs for a fixed engine RPM allowing fine tuning. An inertia dyno, even with creative use of the brakes, cannot mimic this.
Use its #s for an estamate of actual propelling force with all factors in.
If I want that I'll just go to a track. They have correction factors, the track is consistent etc. No, I just want to know how much power is available at the hubs, pure and simple. No wind this, no drag that, no weight the other...just power.
rwHP = HubTorque*HubRPM/5252.
The DJ gives that, the MD for whatever reasons does not.
NO dyno is completely acurate, that small guess work is no big deal.
I agree that there's uncertainties in everything. Even two DJ may give slightly different readings...like every scientific instrument, they rely on calibrations, maintenance and the like to give optimal results. However, in principle, the DJ is about the simplest, most determinist way to measure the work your engine can do via the road wheels.
What you car makes on a dyno doesnt meak squat...its just for fun and a comparison.
Well, my Ford Probe GT put down a whole 135 front-wheel HP. That's just how fast it could spin those 2000-lb rollers up to speed. It's directly comparable to my 268 rear-wheel HP Mustang or the 1500HP blower BBC that was on my favorite dyno last weekend. In all instances these three powerplants are trying to do work on a known system. Their results are eminently comparable, in terms of power they put down.
My reasons were A. to check A/F #1
I agree: the MD is invaluable for tuning.
and B. to see how my car stacked up against other cars, to see if my car is performing like it should.
I can do this on the track or on the street once in a while though.
MD is absolutly the best for tuning though, cant beat it.
Agreed.
Dyno jet lets you see how you stack up against everyone else...and see what HP your car is making as compared to what its advertised.
They DJ is good for two reasons. First, as you note, it's "universal". A 248C with 2000# rollers in one site is pretty much the same deal everywhere else and as long as all units are calibrated and maintained, their numbers are directly comparable. Second, it's giving an accurate measure of the power available at your wheels. No fudges, no estimates, just power.
Oh and that wind resistence is used to calculate actual real world conditions.
But I can get real world conditions in the real world.
Like flying down the highway at 100MPH...it gives a good guess as to what your A/F will be and how your car is running. A DJ cannot reproduce real world A/F #s and the such.
Well "wind resistance" isn't needed to tune AFR. That can be done simply by loading the tires at any given RPM to allow tuning of the AFR at various throttle angles. If that means 4000RPM in 4th, so be it. It doesn't have to be masked under "wind resistance"...it's simply "load tuning."
And the DJ, being an interial unit, doesn't have to try to reproduce wind resistance when all I want it to tell me is power at the wheels.
The car usually runs on the rich side due to the car being under less load. Personally I am getting my car TUNED next month after the cams on a MD...
I wouldn't recommend any other way to tune it. MD rocks for that. But it, for whatever reason, will not give accurate, absolute power-at-the-wheels numbers if you want them.
but a few weeks after I am going back to the dodge DJ to see my GAINS. As i cannot see how much power I gained when on the MD.
No need to roll your eyes at me
